German Patent Application No. 33 35 169 describes a fuel injection valve, in which a spherical valve element having a plurality of flattenings (truncated sections) on its periphery is installed as a valve-closure member to allow fuel to flow around the sphere and thus arrive at the valve seat. The flattenings on the spherical valve-closure member are needed when the valve-seat body has a complete ring guide for positioning and aligning the valve-closure member, since otherwise the fuel would dam up at the sphere and not flow through to the valve seat. The flattenings introduced on the periphery of the valve-closure member are formed in a circular shape and are not spatially associated with the spray-outlet orifices provided on the downstream end of the injection valve.
A fuel injection valve having a valve-closure member of a similar design is described in German Patent No. 42 30 376. Here as well, the circular flattenings on the surface area of the spherical valve-closure member have the function of allowing fuel to flow out of an inside valve space, into which the valve needle extends, to spray-outlet orifices of the injection valve. In this case, there is no fixed association between the flattenings on the valve-closure member and the-spray-outlet orifices. On the contrary, the torsional position of the valve needle, and thus of the valve-closure member, is arbitrary, and therefore, also varies among the individual injection valves of a production series. The flow of oncoming fuel to the individual (e.g., four) spray-outlet orifices is also determined by the flattenings.
A spray-outlet orifice is supplied more efficiently with the medium to be sprayed off when a flattening is situated directly upstream. However, if a guide edge, formed between two flattenings, is located above the spray-outlet orifice, then the result can be that the spray-outlet orifice is insufficiently supplied. The irregularity (unevenness) of the oncoming flow in the circumferential direction thus brings about a change in the flow rate and an increased variance in the static flow rate relative to the rotational position of the valve needle.
A fuel injection valve having a spherical valve-closure member (globe valve) is described by U.S. Pat. No. 4,520,962. This valve-closure member has no means on its periphery for fuel to flow past. On the contrary, the fuel flows immediately upstream from the valve seat, coming from the side, directly to the valve-closure member. An additional spiral member having spiral-shaped grooves is provided downstream from the valve seat, in which case the grooves apply a rotational energy to the fuel. The fuel is then sprayed off through a single outlet orifice.
Additionally, U.S. Pat. No. 5,199,648 describes a fuel injection valve, in which a valve-closure member that is securely joined to the valve needle, has a plurality of grooves running at an angle to the longitudinal valve axis. The depth of the grooves can be constant over the entire length or be diminished toward the ends of the grooves while the deepest spots are in the middle of the grooves. The grooves differ from the flattenings in that they no longer run only directly on the surface of the valve-closure member, but have groove bottoms that lie more deeply in the material. In addition to the opening and closing on the valve seat, the spherical valve-closure member also fulfills the function of valve-needle guidance. The grooves serve to allow the medium to flow through from the inside valve space to the valve seat, a rotational energy being applied to the fuel by the angled grooves, and a better atomization supposedly being achieved. The fuel then emerges downstream from the valve seat through a centrally arranged spray-outlet orifice; thus, it is not distributed among a plurality of spray-outlet orifices. The disadvantage of this groove formation is that the total fuel flowing from the inside valve space to the valve seat is heavily deflected therein and suffers a loss of pressure, since the grooves effect a substantial resistance to flow.